In an assembly line of products or a delivery location of articles, conveyer lines are often utilized for conveying a conveyed object. For example, a number of conveyer lines are installed vertically and horizontally in the delivery location, and a transfer device is disposed at a position where the conveyer lines cross each other. In other words, the transfer device has a function of carrying out an article from an original conveyer line (a main conveyer line), and transferring the article to another conveyer line (a sub conveyer line), thereby conveying the article to a desired location.
Also, in order to perform the above-described function, the transfer device includes two conveyer units for conveying the article and a lifting and lowering unit for changing a height position of the conveyer unit. The two conveyer units respectively have conveying passages for placing and conveying the conveyed object. The conveying passages of the two conveyer units have mutually different conveying directions. The transfer device is configured so that relative heights of the two conveying passages can be changed by the above-described lifting and lowering unit.
In other words, in this type of transfer device, a top surface of the conveying passage of the conveyer unit which is not involved in the conveyance is retreated downward from a conveying surface of the conveyer line by the lifting and lowering unit. Moreover, a top surface of the conveyer unit which contributes to the conveyance is lifted and exposed as a conveying surface of the conveyer line by the lifting and lowering unit. Also, smooth conveyance is realized without being obstructed by the conveying unit which is not involved in the conveyance, by operating (driving) the conveyer unit that is lifted as the conveying surface.
Further, in recent years, there has been a case where conveyer lines are sterically constructed in the delivery location or the like to effectively utilize a floor area. In other words, a conveyer line in a first floor part, a conveyer line in a second floor part, or further, conveyer lines in multi-stages are disposed to deliver an article to a desired position.
In a case where the article is transferred from the conveyer line in the first floor part to the conveyer line in the other floor, a lift disclosed in Patent Document 2 is used, for example.